The overall objective of this proposal is to localize chromosomal loci (and ultimately genes) that interact with specific environmental exposures to modify risk factors for CVD using state-of-the-art molecular and statistical genetic approaches in the Old Order Amish, a unique closed founder population who are relatively genetically homogeneous, and have very large family sizes and well documented genealogies. Since February 1995, Dr. Shuldiner and his coworkers have recruited and studied over 2500 Amish individuals, 1,000 of whom are participants of Amish Family Calcification Study (AFCS), a study designed to examine independent and joint genetic influences on osteoporosis and coronary artery disease. Extensive phenotypic characterization of AFCS participants include blood pressure, body composition, bone mineral density, lipids, and coronary artery calcification by electron beam CT. DNA already has been collected on all AFCS subjects and a 5-cM genome scan (approximately 800 short tandem repeat (STR) markers) will be completed by Summer 2002. The Specific Aims of this proposal are: (1) To perform four focused short-term interventions and to measure CVD responses in subjects of AFCS including high fat meal and changes in endothelial function as assessed by flow-mediated vasodilation (FMD) studies; cold presser stress and changes in FMD and blood pressure; a high salt and low salt diets and changes in blood pressure; and aspirin therapy and measures of platelet function; (2) To characterize the genetic epidemiology of the CVD related response to each short-term intervention; (3) To identify specific chromosomal loci that influence CVD related responses to the four interventions by performing genome-wide linkage analysis (4) To identify and localize chromosomal regions and genes influencing CVD related responses by exploiting the extended linkage disequilibrium in this relatively young founder population to perform LD mapping with densely distributed single nucleotide polymorphisms (SNPs) within linked regions; and (5) To determine if chromosomal regions linked to, or associated with, variation in CVD trait responses are also linked to, or associated with, variation in coronary artery or aortic calcification. Discovery of context-dependent CVD genes will provide (i) critical insights into molecular mechanisms and new molecular targets for therapeutics; (ii) clinically useful information that will allow physicians to individualize pharmacological and non-pharmacological therapy, and (iii) blood tests for the early detection of susceptibility individuals so that targeted preventative interventions can be instituted. These advances will impact substantially on the quality of life of millions of older Americans with CVD.